| |
 |
| Paper: |
The Infancy of Massive Stars: Looking into the Cradle |
| Volume: |
267, Hot Star Workshop III: the Earliest Stages of Massive Star Birth |
| Page: |
95 |
| Authors: |
Kaper, L.; Bik, A.; Hanson, M. M.; Comerón, F. |
| Abstract: |
With the aim to directly detect the photospheres of newly born, massive stars, we have obtained near-infrared spectra of the deeply embedded, candidate ionizing stars of (ultra-)compact HII regions with the Very Large Telescope. The targets were selected on the basis of their near-infrared luminosity and colour measured from narrow-band images collected in a survey of 45 southern UCHII's. Although the UC HII sample was compiled using the IRAS-colour criterium of Wood &Churchwell, the association with ultracompact (radio) sources, and therefore the secure identification with infant HII regions, is often not obvious. However, the K-band spectroscopy confirms the OB-star nature of 36 strongly reddened stars, among them O stars of very early spectral type. Another twenty stars do not show photospheric absorption lines, but include a strong and broad Brγ emission line. These stars share characteristics with objects classified as massive YSOs (such as, e.g., in M17). We present arguments that they are likely surrounded by a circumstellar disk. |
|
|
|
|
|
